Preparation of metal titanate



United States Patent PREPARATION OF METAL TITANATE Leon Merker, Bronx, N. Y., assignor to National Lead Company, New York, N. Y., a corporation of New Jersey No Drawing. Application September 18, 1953, Serial No. 381,114

3 Claims. (CI. 23-51) This invention relates to a novel finely divided nickel titanate composition of matter especially adapted for use as a starting material for the preparation of single crystals of nickel titanate.

in prwaration of single crystals in general, it is necessary to employ a raw material which conforms to necessary requirements, such as for example, purity and particle size. in preparing the various raw materials for making single crystals, it is difiicult to obtain the high quality demanded for single crystal production.

Nickel titanate is normally prepared by calcining a mixture of titanium dioxide and nickel oxide at elevated temperature. The type of titanate produced by this method, however, is not of suficient purity to be used as raw material for single crystal production even though C. P. Grade (chemically pure) raw materials, which are the purest commercially available, are employed. The C. P. Grade raw materials invariably have quantities of certain impurities including the alkali metal compounds present which apparently cannot be conveniently or readily removed. When produced by calcining titanium dioxide and an oxide of nickel, the titanate usually is not homogeneous and therefore varies from the theoretical composition throughout the mass. Furthermore, this type of material does not possess the necessary particle size for single crystal production.

An object of this invention therefore is to provide a nickel titanate composition which is capable of being used as raw material in forming titanate single crystals. A further object is to provide a simple method for the production of high quality nickel titanate composition. Another object is to provide a method by which nickel titanate of extraordinary purity may be produced from commercially available raw materials which will be suitable for production of single crystals. Another object is to provide a product which has a relatively high bulk density which possesses good free-flowing characteristics. These and other objects will become apparent from the following more complete description of the present invention.

In its broadest aspects this invention contemplates finely divided nickel titanate of a character adapted for the manufacture of single crystals. Such a composition will comprise a free-flowing finely divided subtsantially pure, substantially uniform titanate of nickel which is formed by calcination of a precipitated double salt and is characterized by an ultimate unit particle size between about 0.1 and 1.0 micron, a majority of said particles being present in aggregated form, the aggregates being of size to pass through 100 mesh screen, but retained on 325 mesh screen. Such material will have a bulk density of between about 46 and about 60 lbs. per cubic foot. This invention further contemplates a method for the production of substantial pure nickel titanate which comprises first forming the double salt, nickel titanium sulfate [NiTi(SQ4)3l and subsequently calcining this compound until the sulfate values are removed and nickel titanate, NiTiOs, composition is obtained.

"ice

In preparing this composition it is preferred to separately prepare solutions of titanium sulfate and nickel sulfate, admixing the solutions and concentrating the mixture to $03 fumes to precipitate the double salt. The precipitate when formed should be washed thoroughly, preferably with dilute acid, :until the filtrate is free from soluble sulfates.

The calcination of the double salt composition is not critical except for obtaining at least a minimum temperature which will substantially, completely destroy the sulfate values from the composition. It has been found that a minimum temperature of about 1100 C., and preferably from about 1300 C. to 1500 C., is necessary to destroy the sulfate values and to form the homo geneous nickel titanate compound.

By the use of this method, satisfactory purity of the nickel titanate has been obtained when employing C. P. Grade (chemically pure) raw materials. Certain impurities, including the alkaline earth metal compounds, usually are present in excess of the tolerable amount in most C. P. materials, but the excess is readily removed during the precipitation and washing of the precipitated double salt. This method produces substantially pure nickel titanate from C. P. Grade raw materials, while the prior art methods cannot produce substantially pure titanates from such commercially available high grade materials. A soft calcined product is obtained and when it is screened through mesh screen it possesses good free-flowing properties and its bulk density falls within the desired range. Such material is readily adaptable for the manufacture of titanate single crystals.

The bulk density of the calcined nickel titanate product was determined on a Scott Volumeter. This procedure is described in detail on page in 1949 Book of A. S. T. M. Standards, part 4.

Since there are no standard tests for measuring the free flowing characteristics of such a material, the following est was developed.

A container 1 inch in diameter and 1 inch in height was filled (leveled off) with the calcined titanate material. The bottom of the container was held 12 inches from the table top by placing it on a suitable stand. The bottom of the container consisted of a trap door which was sprung open to permit the titanate powder to flow onto the table. The free-flowing characteristics were measured as the distance the material flowed from a point directly beneath the center of the container. The distance was measured in inches from the point. This distance is equal to the radius of the circular pattern formed by the flow of the material on the table. The nickel titanate material prepared by this invention flowed on the table to form a circle having a radius between five and ten inches.

In order to more fully illustrate the instant invention, the following example is presented:

Preparation of titanium sulfate solution In order to prepare a titanium sulfate solution, 6.5 parts of finely divided and substantialy pure titanium dioxide were added to 45 parts of hot concentrated (96%) sulfuric acid containing 12 parts of ammonium sulfate. The mixture was heated to boiling until a clear solution was obtained.

Preparation of nickel sulfate solution 31.5 parts of C. P. Grade nickel sulfate, NiSOr-6H2O, were dissolved in 309 parts of concentrated HCl and the mixture heated until a clear solution was obtained.

Preparation of double salt nickel titanium sulfate The solutions of titanium sulfate and nickel sulfate were then admixed with stirring, while hot, and were turned cloudy. Upon further heating, a dense crystalline precipitate of the double salt nickel titanium sulfate was formed. Heating was discontinued after 12 hours. The precipitate was then filtered on a vacuum filter and the filter cake was washed with dilute HCl until the wash liquor was free from sulfates. The filter cake'was then air dried for 4 hours.

The dried cake was calcined at 1400 C. for 2 hours to destroy the sulfate values and to form nickel titanate. The calcined material Weighed 19 parts which represents 95% recovery of the titanium values. The product analyzed 51.7% TiOz, 48.1% 'NiO, 0.l% alkali metal oxides, 0.1% alkaline earth metal oxides and 0.08% silica. An X-ray of the final product showed only nickel titanate pattern. The calcined nickel titanate material was screened through a 100 mesh screen and the size of the aggregates was found to be as follows:

Sieve size, Percentage mesh Substantially all of the individual particles fell within the range between 0.1 and 1.0 micron. The bulk density of this material was 45 lbs. per cubic foot. With respect to the free-flowing characteristics, this product has a spread of 6 inches radius.

A single nickel titanate crystal was prepared by the flame fusion method from the nickel titanate produced in this example.

The type of product produced by the instant process is finely divided and homogeneous and has the characteristics of being free-flowing. An average particle size of the nickel titanate product lies between 0.1 micron and 1.0 micron. Substantially all of the individual particles are present in the form of aggregates which fall Within the heated'until heavy S03 fumes appeared and the solution sulfate solution is prepared by admixing finely divided range between'lOO and 325 mesh. The bulk density lies between about 40 and about lbs. per cubic foot. In order to be useful, particularly for the manufacture of single crystals, the material .must possess good free-flowing properties, high bulk density, small individual particle size, and substantially all of the particles in aggregated form. Such characteristics are essential in the material to be employed for the manufacture of single crystals. This titanate product has been prepared from raw materials which normally are not sufliciently pure to produce a substantially pure titanate product.

While this invention has been described and illustrated by the examples shown,.it is not intended to be strictly limited thereto, 'andother. modifications and variations may be employed within the scope of the following claims. Eclaim:

1. Preparation of finely divided nickel titanate adapted.

temperatures until the sulfate values are destroyed and V the nickel titanate compound is obtained. 7

2. Method according to claim 1, in which the titanium titanium dioxide in a hot concentrated solution of sulfuric acid containing ammonium sulfate.

3. Method according to claim 1 in which the double salt is calcined at temperature from about 1100 C. to 1500 C. to form nickel titanate compound.

References Cited in the file of this patent UNITED STATES PATENTS 2,140,236 Lederle Dec. 13, 1938 2,166,221 Patterson July 18, 1939 2,218,655 Peterson Oct. 22, 1940 OTHER REFERENCES Mellor: Comp. Treatise on Inorganic and Theoretical Chem., vol. 7, pages 91-95 (1927).

Barksdale: Titanium, copyright 1949, pages 73-76, Ronald Press Co., New York City. 

1. PREPARATION OF FINELY DIVIDED NICKEL TITANATE ADAPTED FOR THE MANUFACTURE OF SINGLE CRYSTALS WHICH COMPRISES ADMIXING TITANIUM SULFATE SOLUTION AND A NICKEL SULFATE SOLUTION AND CONCENTRATING SAID MIXTURE TO SO3 FUMES TO PRECIPITATE A DOUBLE SALT OF NICKEL TITANIUM SULFATE, FILTERING AND DRYING SAID PRECIPITATE AND CALCINING AT ELEVATED TEMPERATURES UNTIL THE SULFATE VALUES ARE DESTROYED AND THE NICKEL TITANATE COMPOUND IS OBTAINED. 